I think a lot of it boils down to what you expect out of a video game's story.

I go into video games expecting the kind of story you get in a summer action blockbuster. The plot that's obviously just there to tie action scenes together and you're lucky if your main character has any kind of character growth. RPG games I do expect to see character growth and a plot that's a bit more than just to tie the "action scenes" together.

I do have issues with all of the expansion stories and think some things could have been handled differently. It's just not the point that it significantly impacts my enjoyment of the story. Because just looking for a touch of actual plot and some character growth. Which we have gotten in all expansion packs.

Some people go into games wanting the quality of stories you would get if you picked up a good book and started reading it. Strong plot and good character growth of the main cast.

And neither side is wrong in their approach to video game stories, especially those in the RPG genre.

Could the character growth of the main cast be stronger? Yes. That's a fact. Whether or not said fact has any impact on whether or not a game is enjoyable or not to an individual is subjective. No one is wrong if they say the game is immensely enjoyable despite its flaws in storytelling. No one is wrong to say that the flaws in the storytelling have hurt their enjoyment of the game.

Could the story be stronger if there was a main cast shake up? Yes. Is it wrong to enjoy the current main cast and hope that they stick around for awhile? No.

Does the OP have points about Alphinaud's character development? Possibly. To know for sure on how I stand on that, I'd have to stop and analyze the story and analyzing stories isn't fun for me and would reduce my enjoyment of the story overall. Again goes down to what I go into a video game for story wise. You don't analyze an action blockbuster movie's plot.